As depicted in FIG. 1, an organic light-emitting device (OLED) 100 may include a layer of indium tin oxide (ITO) as an anode 102, a layer of hole-transporting materials (HTL) 104, a layer of emissive materials (EML) 106 including emitter(s) and host(s), a layer of electron-transporting materials (ETL) 108, and a metal cathode layer 110 on substrate 112. The emission color of OLED 100 may be determined by the emission energy (optical energy gap) of the emitter(s) in the layer of emissive materials. Phosphorescent OLEDs (i.e., OLEDs with phosphorescent emitters) may have higher device efficiency than fluorescent OLEDs (i.e., OLEDs with fluorescent emitters). Some emitters for blue phosphorescent OLEDs include iridium—a relatively scarce element—in the form of cyclometalated iridium complexes.